Comment on “High Naturally Occurring Radioactivity in FossilGroundwater from the Middle East”

Vengosh et al.1 conducted a study on the Disi aquifer inJordan in order to understand how salinity is correlated

with radioactivity, to evaluate the sources of radium in thegroundwater and to investigate the possible mechanisms ofradium mobilization. The activity concentration of three α-emitting isotopes, namely 226,224,223Ra, in addition to the β-emitting 228Ra, were measured in thirty-seven groundwatersamples. The study covered the Rum-group aquifer, theKhreim-group in Disi-Mudawwara and areas in Central Jordan.That study ultimately revealed the Disi water to be highlyradioactive, thus surrounding the Disi conveyance project withcontroversy. The paper reported the combined 226Ra and 228Raactivities to be much higher than international drinking-waterstandards. The reported data raised concerns over the safety ofDisi and similar nonrenewable groundwater reservoirs,intensifying the already severe water crisis in the region. Thatimportant paper was cited not only in different reports (e.g.,refs 2−4), but also repeatedly in local and international media,hence became the focus of attention for a continued debateover the indispensable Disi conveyance project. Jordan hasalready one of the lowest levels of water resource availabilityper capita in the World. Management of water resources istherefore a key issue facing national government authorities.5,6

In July 2013, Jordan began pumping water from the southernfossil aquifer of Disi, a $990 million project which involvesdigging 55 wells and piping water supplies 325 km to the capitalcity Amman, as well as to other governorates. The lifespan ofthis nonrenewable water conveyance project is estimated at20−30 years if abstraction rates are kept at around 100 millioncubic meters (mcm) each year. The project hence provides aprovisional solution to a long-term problem, but providesJordan with enough time to consider other options likedesalination.5 Therefore, the Disi resource is of vital importanceto the country, especially amid the unrest in the region whichimposes direct multifold impact on Jordan, one of which isrelated to hosting significant numbers of refugees.The hydrogeological nature of that study did not require the

calculation of the corresponding effective dose delivered toconsumers. Therefore, Table 1 of the Vengosh et al. paper onlylists the measured activity concentration (in Bq/l) for the fourradium isotopes. Though the table compares these activityconcentration values to the corresponding internationalrequirements and guidelines on activity, but no dose calculationand comparison with international standards was implied atthat stage by the objectives of the Vengosh study.The current comment aims at a further analysis of the same

raw data reported in Table 1 of the Vengosh et al. paper. Inaddition to radioactivity concentration, this work evaluates thecommitted effective annual dose from the radium isotopes. Thedose is calculated from the individual radionuclide concen-tration assuming annual consumption of 730 L.7 Theradiotoxicity of a nuclide is determined by its effective dosecoefficient, which accounts for radiation and tissue weightingfactors and metabolic information. The coefficients are

obtained from the International Commission on RadiologicalProtection ICRP 2012 report.8 Private communication with theWater Authority of Jordan WAJ indicated that water currentlypumped from the wells arrive at the reservoirs after a minimumperiod of 2.7 days. Though this period does not include anadditional time to reach households through the distributionnetwork, the 2.7 days period was adopted for a conservativeestimate of the decay of the relatively short-lived radiumisotopes, namely 223Ra and 224Ra, with half-life times T 1/2 of11.435 and 3.66 days,9 respectively.The activity concentration screening levels of 0.5 Bq/L for

gross-alpha and 1 Bq/L for gross-beta, as set by the WHO,7 areobviously exceeded. Since consumption of radium in drinking-water increases risks for bone cancer and leukemia, it was notedthat many Rum-group wells exceed the derived concentrationof 0.5 Bq/L (or 1 Bq/L) for 226Ra and most Rum-group wellsexceed the derived concentration of 0.2 Bq/L (or 0.1 Bq/L) for228Ra, as set by the European Union10 (or in the WHOguidelines7). The combined 226Ra and 228Ra activities alsoexceed the U.S. EPA limit of 5 pCi/L.11 Consequently, thecommitted effective annual dose from individual radionuclidesare considered (Figure 1). Obviously, the annual dose from the

Rum-Group as well as from Central Jordan wells is highcompared to the 0.1 mSv/a recommended in the WHOGuidelines.7 It is worth mentioning that in October 2013, theEuropean Union adopted the same WHO guideline value of 0.1mSv/a.10 Nevertheless, the very same WHO report emphasizesthe fact that “It is essential that each country review its needsand capacities in developing its regulatory framework”. It alsomentions that no international standards for drinking-waterquality are promoted for adoption. In particular, the report

Published: July 31, 2014

Figure 1. Dose contribution of the four radium isotopes for individualwells in each of the Disi aquifer groups. A conservative delay period of2.7 days for water pumped from each well to reach the collection/mixing reservoir has been assumed.

Correspondence/Rebuttal

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© 2014 American Chemical Society 9943 dx.doi.org/10.1021/es5005736 | Environ. Sci. Technol. 2014, 48, 9943−9945

emphasizes that exceeding a guidance level should be taken as atrigger for further investigation, but not necessarily as anindication that the drinking-water is unsafe. The above-mentioned guidelines on activity concentration of 1 Bq/Land 0.1 Bq/L for 226Ra and 228Ra, respectively, are derived fromthe recommended dose of 0.1 mSv/a.In this context, the 2011 Australian Drinking-Water Guide-

lines12 recommends a guideline dose of 1 mSv per year to beapplied. This is ten times the corresponding WHO value. TheAustralian document does not consider its recommended doseas a mandatory limit, but when exceeded, a decision on theneed for remedial action should be based on a cost−benefitanalysis, and there may be circumstances where there is nopractical alternative but to accept a dose that exceeds thisguideline. The Australian guideline value is based on earlierstudies.13,14 In Jordan, however, a mandatory regulation sets amaximum dose of 0.5 mSv/a,15 which if exceeded, a limitedtime period is allowed to consider operational options to securecompliance.Therefore, in addition to the WHO guideline, both

Australian guideline and Jordanian standard values are indicatedin Figures 1 and 2. The average dose from each group is

depicted in the white column (solid border) of Figure 2. Waterfrom the Khreim-group could comply with the conservativeWHO recommendation, while the average dose from CentralJordan wells could satisfy the Jordanian standard. Theunconfined and confined Rum-group slightly exceed theJordanian dose limit and the Australian guideline, respectively.Needless to say, water treatment could considerably reduce

radium concentration and hence the associated dose to levelswell below the Jordanian standard. This was also recommendedby Vengosh et al. An alternative cost-effective solution couldpotentially be considered, that is, to develop a crude model forblending groundwater with, for exmaple, surface water in a localreservoir. This is intended to provide a qualitative assessmentabout the effectiveness of such mixing on reducing the dose toconsumers. To make this model as conservative as possible, adose of 0.15 mSv/a is adopted for the non-Disi resource,16

which is already higher than the WHO recommendation.Mixing ratios of Disi:Non-Disi = 1:1, 2:1 and 1:2 areconsidered and depicted in Figure 2. According to such veryconservative models, a dose of less than the WHO guideline isdefinitely not achievable. Nevertheless, and instead of exceeding

Jordanian standards for part of the population, while the otherpart continues using lower-activity non-Disi water, mixing aimsat achieving compliance with the Jordanian standard for allconsumers in the country.The results reveal the radiological quality of the indispen-

sable Disi drinking-water to be satisfactory for consumption in awater-poor part of the World, if risks are carefully managed.The author is preparing an extended manuscript that includes arisk-benefit analysis. Blending ratios should take intoconsideration any possible buildup of the nonmobile 228Th inthe system, which could affect the 224Ra concentration.Continuous and routine monitoring, including samplecollection and measurement, is essential to ensure compliancewith the local standards. Transparency in the governmentalwater policies psychologically enhances the public acceptance.Practically, decision on blending ratios should always take intoconsideration the importance to reduce risk as much asreasonably achievable. However, the availability and quality ofsurface water, to a given reservoir, could be a limiting factor.Water treatment facilities should be considered locally inregions with limited availability of surface water resources.Proposals for water desalination in the Gulf of Aqaba, which isintended to provide a more sustainable supply, can be alsoconsidered as a future resource for blending which can takeplace on-site in the south, eliminating the necessity for regionalblending. This scenario enables freeing surface water resourcesto be available to other usage.

Saed Dababneh*Department of Physics, Faculty of Science, Al-BalqaApplied University, P.O. Box 2587, Amman 11941, Jordan

■ AUTHOR INFORMATION

Corresponding Author*Phone: +962-7-95606613; fax: +962-6-5341608; e-mail:dababneh@bau.edu.jo.

NotesThe authors declare no competing financial interest.

■ REFERENCES(1) Vengosh, A.; Hirschfeld, D.; Vinson, D.; Dwyer, G.; Raanan, H.;Rimawi, O.; Al-Zoubi, A.; Akkawi, E.; Marie, A.; Haquin, G.; Zaarur,S.; Ganor, J. High naturally occurring radioactivity in fossilgroundwater from the Middle East. Environ. Sci. Technol. 2009, 43,1769−1775.(2) Upson, S. Jordans radioactive water problem. Spectrum IEEE2009, 46, 13−15.(3) Bonotto, D. M. Natural radionuclides in major aquifer systems ofthe Parana sedimentary basin, Brazil. Appl. Radiat. Isot. 2011, 69,1572−1584.(4) Szabo, Z.; dePaul, V. T.; Fischer, J. M.; Kraemer, T. F.; Jacobsen,E. Occurrence and geochemistry of radium in water from principaldrinking-water aquifer systems of the United States. Appl. Geochem.2012, 27, 729−752.(5) Jaber, J. O.; Mohsen, M. S. Evaluation of non-conventional waterresources supply in Jordan. Desalination 2001, 136, 83−92.(6) World Health Organization. HELI Technical Advisory Group inJordan. http://www.who.int/heli/pilots/jordan/en/ (accessed Sep-tember 2013).(7) Guidelines for Drinking-Water Quality, 4th ed.; World HealthOrganization, 2011.(8) Compendium of Dose Coefficients Based on ICRP Publication 60,ICRP Publication 119. Ann. ICRP 41 (Suppl.); The InternationalCommission on Radiological Protection, 2012.

Figure 2. Average radium dose according to three mixing models withnon-Disi water with a conservative 0.15 mSv annual dose.16

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(9) Chu, S.; Ekstrom, L.; Firestone, R. WWW Table of RadioactiveIsotopes, The Lund/LBNL Nuclear Data Search, Version 2.0, 1999.http://nucleardata.nuclear.lu.se/toi/index.asp (accessed September2013).(10) COUNCIL DIRECTIVE 2013. Laying down requirements forthe protection of the health of the general public with regard toradioactive substances in water intended for human consumption.http://register.consilium.europa.eu/pdf/en/13/st07/st07445-re03.en13.pd.(11) US-EPA Drinking water: Radionuclides Rule. http://water.epa.gov/lawsregs/rulesregs/sdwa/radionuclides/compliancehe.(12) Australian Drinking Water Guidelines 6; Australian NaturalResource Management Ministerial Council, National Health andMedical Research Council: Canberra, Australia, 2011; Vol. 1.(13) Recommendations for Limiting Exposure to Ionising Radiation,Radiation Health Series No. 39, Government Publishing Service, Canberra;NHMRC National Health and Medical Research Council: Canberra,Australia, 1995.(14) Lokan, K. Drinking water quality in areas dependent ongroundwater. Radiation Protection in Australasia 1998, 15, 11−14.(15) Technical Regulation (Mandatory) 286/2008 on Water - DrnkingWater (in Arabic); Jordan Standards and Metrology Organization:Amman, Jordan, 2008.(16) Al-Amir, S. M.; Al-Hamarneh, I. F.; Al-Abed, T.; Awadallah, M.Natural radioactivity in tap water and associated age-dependent doseand lifetime risk assessment in Amman, Jordan. Appl. Radiat. Isot.2012, 70, 692−698.

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